1. Field of the Invention
This invention relates broadly to ophthalmic lens treatment technology. More specifically, this invention relates to contact lens disinfecting devices in which gas is liberated during the disinfection process.
2. Description of the Related Art
Contact lenses provide the consumer with an exceptionally convenient alternative to spectacles or glasses, a more archaic form of vision correction. However, proper maintenance of contact lenses require periodic sterilizing or disinfecting to eliminate harmful bacteria or fungi, and cleansing to remove deposits such as proteins or lipids which adhere to the lens. In order to clean and/or disinfect contact lenses, a wide variety of devices have been developed.
A particularly efficacious method of disinfecting contact lenses is by a chemical treatment of the lenses with a hydrogen peroxide solution, as described in U.S. Pat. No. 3,912,451, issued to Gaglia, Jr., Oct. 14, 1975. In a typical lens disinfecting apparatus, contact lenses are placed in hydrogen peroxide solution inside a container. The container is sealed (e.g., by threads on the container mating with threads on a cap) for a predetermined period of time to sufficiently disinfect the lenses, with the seat preventing liquid spillage resulting from container movement.
Although hydrogen peroxide is highly effective in disinfecting contact lenses, hydrogen peroxide must be removed from lenses prior to placing the lenses in a patient's eye in order to avoid patient discomfort. One method of removing hydrogen peroxide involves contacting the hydrogen peroxide with a platinum catalyst, thereby rapidly decomposing the hydrogen peroxide into water and gaseous oxygen. Liberated gaseous oxygen resulting from the peroxide decomposition generates internal pressure in the cleaning container which must be vented. In order to alleviate this pressure, a wide variety of venting means have been developed.
For example, U.S. Pat. No. 4,637,919, issued to Ryder, et al., Jan. 20, 1987, discloses a contact lens cleaning container and mating cap, where the cap includes a filter assembly positioned in a vent passageway. The filter assembly includes a hydrophobic membrane which continuously vents the gas generated within the container during the decomposition of peroxide. The pores in the hydrophobic membrane are sufficiently small to inhibit liquid leakage from the container.
U.S. Pat. No. 4,750,610, issued to Ryder, Jun. 14, 1988, discloses a disinfecting container which is affixed to a cap via loose threading. The cap includes a resiliently deflectable flange which acts as a check valve in conjunction with the container. In operation, the cap flange is typically in a closed position, i.e., the flange is positioned immediately adjacent a portion of the container, thereby preventing liquid leakage. When excess internal pressure develops, the cap flange deflects, allowing gas to pass through the loosely threaded container-cap connection to the outside of the container.
U.S. Pat. No. 4,956,156, issued to Kanner, et al., Sep. 11, 1990, discloses a disinfecting system which includes a cap having a bore. A post is positioned in the bore with a resiliently-deflectable diaphragm positioned around the post. The diaphragm-post seal prevents liquid leakage, while allowing gas to pass upon deflection of the diaphragm when sufficient internal pressure develops.
U.S. Pat. No. 4,996,027, issued to Kanner, Feb. 26, 1991, discloses a disinfecting system which includes a container and cap connected by threading. A self-reseating unitary gasket is positioned between the cap and container to provide a liquid-tight seal. Increased internal pressure causes the gasket to unseat, at least partially, allowing gas to pass between the cap and container connection to the environment.
U.S. Pat. No. 5,250,266, issued to Kanner, Oct. 5, 1993, discloses a lens cleaning apparatus, including a container and a cap, in which gas is vented through a type of check valve in the cap. The check valve includes a disc having a linear slit therethrough. The slit generally provides a liquid-impermeable barrier, but when internal pressure is generated, the slit opens to allow gas to pass to the environment.
The previously-described patents describe practical venting alternatives for peroxide-based lens cleaning/disinfecting devices. However, there is a need to provide a less complicated venting system, both from a manufacturing perspective and from an operational perspective.